With the recent release of Windows Vista, you will probably notice pretty quickly, the Gadget SideBar. CNET/Download.com does a good job of explaining this jargon for you.
I might note that any Widget or Gadget you do have running will use some of your computer processes/memory, depending on the amount and incorporated data that it receives will also tax your memory so unless you have lots to spare, you may want to use this sparingly.
